Why am i playing like a big noob in gears ?

Well i have been playing like garbage for the past two days and i have no idea why this is not my first time playing gears i have played all online since gears 1 usually i play king of the hill and come in 1st as the mvp but now im just in last same with tdm i am usually around 1st 2nd or 3rd with a good ratio but now im that player who uses all the spawns with few kills i dont know why im playing bad i tried changing my sensitivity and it didnt hel tried different aiming but its all the same i die and some is just bs i can go up to someone and shoot them at point blank and they dont die and turn around and blow me away i use the gnasher and and i am getting killed like nothing with both shotguns and feels like mine isnt doing anything maybe i should just lay off it for a while do you have any tips3 years ago